The invention concerns scaffold systems.
Most especially, the invention concerns a known, standardized scaffold system, having the following features:
vertical posts;
on the vertical posts there are secured apertured, annular disks spaced along the lengths of the posts at intervals corresponding to the grid pattern of the scaffold system;
horizontally and/or diagonally extending elongate scaffold elements which are fastened to the annular apertured disks by means of coupling heads;
the coupling heads have disk-receiving slots by means of which the coupling heads engage the apertured disks at both the bottom and top faces of the disks;
the coupling heads have key-receiving spaces formed by paired key-receiving openings, the top opening being located above the disk-receiving slot of a respective coupling head, the bottom one being located below the disk-receiving slot, for keys that extend down through the top key-receiving opening, then through a disk aperture, and then through the bottom key-receiving opening of the coupling head;
the keys are each wedged against the radially outer margin of a disk aperture and against the radially inward bearing surfaces of the key-receiving space of a respective coupling head;
the keys are provided at their bottoms with thickened portions that prevent loss of the keys;
the bottom key-receiving openings are broader than the upper end region of the top key-receiving opening;
the lateral boundaries of the coupling heads converge in wedge-like fashion towards the common center axis of the post and associated disks;
the radially inward bearing surfaces of the coupling heads, bearing against the periphery of respective posts, are of part-cylindrical configuration and have a radius equal to the outer radius of the posts;
the radially inward bearing surface of each coupling head has a height greater than or equal to the height of the elongate scaffold elements;
the radially inward bearing surfaces of the coupling heads have through-openings which extend all the way through to the key-receiving spaces in the interiors of the coupling heads;
the coupling heads are made of cast or forged steel;
those coupling heads to which elongate scaffold elements are secured are provided with extensions which are fastened to or welded to such coupling heads and which have a profile such as to extend into and engage the interiors of such elongate scaffold elements;
these extensions have recesses or apertures, and the elongate scaffold elements that engage the exterior of the extensions have deformed regions which are received in such recesses or apertures, or else such elongate scaffold elements are held in mounted position on such extensions by means passing through such apertures, such as screws, rivets, or the like;
the scaffold is generally of rectangular geometry and includes elongate scaffold elements each of which extends horizontally in a single one of the x- and y-directions of the scaffold geometry, but if the scaffold also includes diagonal elongate scaffold elements extending in two or more of the x-, -y, and z-directions, then these latter are at their ends provided with flat tangs having cylindrical bores, with rotary pivot members extending through such bores, these pivot members being parts of coupling heads which are like the coupling heads set forth above but, in contrast thereto, not provided with the aforementioned extensions.
A scaffold system exhibiting the above listed features is known from West German patent DE-PS 24 49 124, as well as being known from very widespread use of the construction there disclosed.
Such scaffolds are in general formed by posts made of steel pipe and elongate scaffold elements made of steel pipe or of other profiled steel stock. In certain instances, use has even been made of scaffolds the constituent pipes and/or elongate scaffold elements of which have been made of light metal, not steel, but this in conjunction with many further structural features and structural particulars not customarily employed. This is chiefly to be attributed to the fact that, with the loads presented to the various junctions of a modular scaffold system, high demands are placed upon such junctions, demands which in actual practice either cannot be realized at all when light metal is used or else can be realized only with great difficulty, and even then only if one employs certain combinations of structural materials and furthermore resorts to various non-customary design particulars.
Accordingly, for modular scaffold systems of this type it is, practically speaking, only steel constructions that find substantial use. However, with regard to portability, erection and dismantling these have the very considerable disadvantage of the heavy weight of their individual structural elements. Especially when doing indoor work, use is very often made of tower-like (i.e., stationary) or transportable (travelling) scaffold structures, e.g. in renovation and repair work, for setting up video or filming equipment that is to be located at a considerable height, and so forth, it being necessary that such scaffold structures be quickly erected, quickly dismantled, and in certain instances moved about, especially in partly or completely dismantled state. Also, there is often a need for scaffold structures that can be very quickly set up in confined spaces, solely by means of manual labor, and without the aid of transport equipment such as forklift trucks and/or hoisting equipment for moving the constituent elements of the scaffold structure to where they are needed; examples are: where the scaffold is to be erected inside a power plant boiler and the various scaffold elements must be introduced through a boiler manhole; or, inside the dust-arrester or antipollution installation within a power plant, in the event of malfunction or clogging of a nozzle or other element it may be necessary to erect a scaffold having one or more platforms. Such scaffolds, with or without platforms, often must be constructed very quickly by a small work crew, often with the elements of the scaffold being handed from one crew member to the next, in bucket-brigade fashion, from outside the installation site to inside the installation site, and then later be dismantled no less quickly, the handing-over of constituent elements then proceeding in the reverse direction. Often, furthermore, and as already said, all this must take place in extremely confined circumstances. In such applications, the ability quickly to erect and dismantle scaffolds is of considerable economic importance. In the examples just given, the repair itself may require only a short time. In that event, it becomes a question of economy, and of considerable inconvenience, if the particular installation must suffer a protracted down-time merely for the purpose of erecting and then dismantling the scaffold needed to make the quickly performed repair.
For such scaffolds, usually of tower-like form but of differing heights, there accordingly exists an especial need for scaffold elements optimized relative to weight, portability, and the configuration of the interconnecting coupling elements.
Furthermore, one should really adopt the view that scaffold elements that are made of light metal, not steel, are to be used wherever possible. In many respects small departures in construction, relative to the structural features of standard scaffold constructions that utilize steel members exclusively, should even be viewed as meriting serious consideration if any can be found that would permit as many of the scaffold elements as possible to be made of light metal. Also, it would be extremely helpful if any such modified scaffold elements could be freely intermixed with the steel elements of standard modular scaffold systems. On the other hand, if one were to resort to such free intermixing, one must be assured that the resulting scaffold structure will be able unproblematically to absorb and withstand the forces to which it will be subjected, especially at the various junctions at which scaffold elements are coupled to one another.